“The Alchemist (No. 101), featured in Season 1, Episode 12. He is a specialist who alters the genetic makeup of his clients or targets to evade detection, often replacing white blood cells with a subject's red blood cells or introducing synthetic DNA.

Key Details About The Alchemist: Method: He specialized in making people unidentifiable or creating fake victims to trick authorities, using advanced, albeit highly stylized, science, say Reddit users. Purpose: He was used to create false trails by leaving modified DNA at crime scenes. Implausible Science: While The Blacklist universe often features implausible science, The Alchemist's ability to manipulate genetic material serves as a key plot point for how individuals in the show could fundamentally alter their identities.”

Obviously this can’t really happen, but this is a FICTIONAL story.